Open source is still a software licence - Digia Qt - (blog) #opensource

The licensing terms are quite different, and provide different value. A lot of companies do not want, or cannot, work through the limitations set by the open source licence agreement, or they feel they do not want to take additional risks and choose the commercial licence for peace of mind. The open source licence, as the name says, is still a software licence and therefore any company using it must understand the terms and work according to them. Companies looking for a strategic framework that enables them to develop risk free; distribute their product as they like while keeping their code proprietary; and have full R&D and support capabilities available to them from a company that makes significant investments into the future of the framework, choose commercial licensing. It provides added value where specific modules, components and support platforms, for example, are ...